A recent incident on a Nairobi bus has highlighted the risks of hazardous noise levels in everyday environments. Alice Wawira, a teacher, used a noise-measuring app to record the bus playing music at an average of 106 decibels, exceeding the 85-decibel threshold for safe volume levels. The app detected a maximum of 114 decibels and a minimum of 94.9 decibels during the journey. Wawira raised the matter with the conductor, but nothing came of it, and she eventually alighted midway through her journey.
Experts warn that prolonged exposure to loud volumes can cause permanent damage to the ears. The United States' National Institute for Occupational Safety and Health advises that at 106 decibels, one should not be exposed for more than three minutes and 48 seconds at a time. Ear, nose, and throat surgeon Dr. Kennedy Kipkoech notes that hair cells inside the ear can snap and fail to recover if exposed to loud noise for too long. This can lead to hearing loss, which can be irreversible if not prevented.
Dr. Kipkoech advises Kenyans to use noise-measuring apps to check whether they are in environments detrimental to their ears. He recommends downloading sound level meters, which average the total noise exposure in a particular place. The doctor explains that sound energy is transmitted into electrical energy for the brain to interpret, and this transformation happens in the inner ear, where hair cells play a key role. If noise is too loud for too long, these hair cells can die, leading to permanent hearing loss.
The World Health Organization advises keeping personal-device volume low, using well-fitting noise-cancelling headphones, limiting time in noisy environments, taking listening breaks, and monitoring sound levels. Dr. Kipkoech notes that normal human speech ranges from 60 to 70 decibels, and people should not dismiss loud music in open spaces or through earphones as a mere nuisance. The higher the decibel level, the higher the risk of hearing loss, and the time factor also plays a critical role in this risk.
In occupational health, 85 decibels over an eight-hour period is commonly used as the threshold at which repeated exposure becomes hazardous. At higher volumes, safe exposure time drops sharply. For example, at 90 decibels, the allowable exposure drops to four hours, and at 95 decibels, it must be halved to two hours. Dr. Kipkoech emphasizes the need for special caution when using personal listening devices, as they deliver sound directly into the ear canal, encouraging long listening sessions without anyone noticing the volume.
Prevention of hearing loss should not rely on willpower alone, especially for those working in noisy settings. Employers and regulators can reduce risk through engineering controls, shorter exposure periods, rest breaks, monitoring, and protective gear such as earplugs or earmuffs. Dr. Kipkoech also cautions against assuming the ear will always recover after a loud event, as chronic exposure can wear out inner hair cells over time. A single extremely loud event can also cause permanent damage to the ears.
Warning signs of hearing loss include needing people to repeat themselves, missing words on the phone, struggling in noisy conversations, and hearing persistent ringing or buzzing. Dr. Kipkoech recommends at least one hearing check-up a year, and more frequent reviews for those regularly exposed to high noise. Hearing aids can help those with hearing loss, but Dr. Kipkoech stresses that this is a preventable condition, and noise-induced hearing loss is permanent if not prevented.
Key points
- Prolonged exposure to loud volumes can cause permanent damage to the ears, leading to hearing loss.
- Experts advise using noise-measuring apps and taking precautions to prevent hearing loss, such as keeping personal-device volume low and using protective gear.
- Employers and regulators can reduce the risk of hearing loss through engineering controls, shorter exposure periods, and protective gear.
